1. Field of the Invention
The subject invention relates to an adaptor to enable precise delivery of small drops of a specimen from a syringe to a point-of-care testing cartridge.
2. Description of the Related Art
Many medical procedures require diagnostic tests to be performed on a sample of a patient's fluid. Fluid often is collected from a patient by employing a needle holder assembly and one or more evacuated tubes. Fluid also can be collected in a syringe. A syringe may be used with a metallic needle to obtain a fluid sample from a patient. However, syringes often are connected directly to an established arterial or venous line to obtain a fluid sample. The fluid collected in the syringe then may be transferred to a tube. The tubes are labeled carefully and shipped to a laboratory for analysis. The results of the laboratory analysis then are reported back to the health care provider. The results, of course, could be rushed in emergency situations, but absent an emergency would require more then one day between the time the sample is drawn from the patient to the time that the laboratory analysis is reported to the health care provider.
Devices have been developed for performing at least certain diagnostic tests on a sample of fluid at the point-of-care. The point-of-care diagnostic equipment includes a syringe for receiving a sample of fluid from a patient, a small disposable testing cartridge for receiving a portion of the fluid from the syringe and a portable clinical analyzer for analyzing the fluid and outputting the results. Combinations of testing cartridges and portable clinical analyzers are marketed in the United States by i-STAT Corporation, AVL Scientific Corporation and Diametrics Medical, Inc. The systems produced by these and other companies share certain common features. In particular, the testing cartridge of each system typically has a small rectangular housing about 1″×2″ and about 0.25″ thick. The housing includes an internal reservoir with a volume of between about 40 μl and 125 μl. An inlet port extends through an external wall of the testing cartridge and communicates with the internal reservoir. The cartridge further includes contact pads and sensors that can be placed in communication with the portable clinical analyzer. An example of an i-STAT point-of-care testing cartridge is shown in U.S. Pat. No. 5,638,828.
The prior art point-of-care testing systems are employed with a syringe that is used to draw a sample of fluid from a patient. The syringe then may be used to eject a portion of the fluid sample into the inlet port of the point-of-care testing cartridge. However, some testing cartridges are operative to automatically draw fluid from the syringe. The inlet port of the cartridge then is closed and the cartridge is placed in communication with the portable clinical analyzer for performing certain specified diagnostic tests on the sample of fluid in the cartridge. The analyzer then provides a very quick output of the test results without the need for sending the fluid sample to the laboratory.
Point-of-care testing systems provide several efficiencies over systems that require virtually all diagnostic tests to be performed at a location remote from the point-of-care. The small size of the testing cartridge facilitates storage and shipment of the cartridges while also contributing to the portability of the system. However, with regards to transferring a collected sample to the cartridge, the small cartridges can be very difficult to use. For example, alignment of the distal end of the syringe with the inlet port of the testing cartridge can be complicated and difficult. A misalignment or imprecise mating of the syringe with the inlet port of the testing cartridge can lead to a loss of a portion of the collected fluid sample. Additionally, it is difficult to use a syringe for accurately dispensing the proper volume of liquid. Too small a volume may prevent proper testing by the cartridge and the associated portable clinical analyzer. Too large a volume can cause splattering or spillage. Similarly an overfill can result in splatter when the cover of the point-of-care testing cartridge is closed. Fluid that is not delivered efficiently from the syringe into the inlet port of the testing cartridge create the potential for disease transmission. Similarly, a loss of fluid during the transfer from the syringe to the testing cartridge can leave an insufficient volume of fluid for performing the required diagnostic tests. An insufficient volume of fluid to perform the required tests can require the health care worker to return to the patient for a second sample of fluid. This is time consuming for the health care worker and traumatic for the patient. Additionally, some testing cartridges may require an insufficiently filled cartridge to be discarded and a new cartridge to be employed with the new sample of fluid. Thus, inefficiencies in the transfer of fluid from the syringe to the testing cartridge can generate excess costs for additional testing cartridges.
The direct transfer of fluid from a syringe to a testing cartridge can cause the syringe tip to close off the entry port and prevent venting of air from the testing cartridge. Thus bubbles are created. Bubbles reduce the volume of fluid and can affect test results.